1. Technical Field
The present invention relates to an electro-optical device and an electronic apparatus.
2. Related Art
There is known an electro-optical device with an electro-optical material (for example, liquid crystal or the like) provided between an element substrate and an opposing substrate. Examples of the electro-optical device include a liquid crystal device which is used as a liquid crystal light bulb of a projector. In such liquid crystal devices, there is demand to realize high efficiency for light utilization.
In the liquid crystal device, TFT elements, wiring and the like for driving pixels are provided outside of a pixel region on an element substrate, and a light shielding layer is provided to overlap these. Therefore, a portion of the incident light is blocked by the light shielding layer and is not used. Therefore, a configuration is known in which, by providing a micro lens array, on which micro lenses are arranged, on at least one of the element substrate or the opposing substrate of the liquid crystal device, the incident light is condensed by the micro lenses and the efficiency for light utilization is increased.
Incidentally, in the liquid crystal device provided with the micro lens array, since the micro lenses are arranged in an orderly (periodic) manner corresponding to the arrangement pitch of the pixels, the incident light is diffracted, diffracted light is easily generated, and the spread of the light which is emitted from the liquid crystal device may increase in size due to the diffracted light interfering with itself. When using the liquid crystal device provided with such a micro lens array as a liquid crystal light bulb of a projector, when the spread angle of the light emitted from the liquid crystal device is equal to or greater than the F number of the projection lens, there is a problem in that a portion of the light is subjected to vignetting by the projection lens and the image which is shown on a screen becomes dark. When the pixel size is reduced as the resolution of liquid crystal devices is increased, since the spread angle of the light increases due to the interference of the diffracted light, the brightness is further reduced.
For the configuration of a micro lens array capable of reducing the influence of such diffraction, a configuration has been proposed in which the period of the orderly array of micro lenses is increased by causing the optical radii of curvature of the micro lenses to differ (for example, refer to JP-A-2005-352392). JP-A-2005-352392 discloses a configuration in which the refractive index differences between the micro lenses and an adjacent member are constant and the radii of curvature of the micro lenses are caused to differ, and a configuration in which the radii of curvature of the micro lenses are the same and the refractive index differences between the micro lenses and the adjacent member are caused to differ. In either configuration, the planar shape of the micro lenses is the same.
However, JP-A-2005-352392 does not disclose a method of forming the micro lens array of the above-described configuration. Forming a plurality of micro lenses with the same planar shape and different radii of curvature in the same process by performing an isotropic etching process using a general mask is considered to be difficult. Even when the refractive index differences between the micro lenses and the adjacent member are caused to differ, the manufacturing process becomes complex due to using materials with different refractive index for each micro lens. Furthermore, when the liquid crystal device provided with a micro lens array in which the shape of curvature or the refractive index difference is caused to differ for each micro lens is used as a liquid crystal light bulb, there is a concern that the image displayed on the screen will become dark. Therefore, there is demand for a liquid crystal device which can effectively reduce the influence of the diffraction of light, and which is provided with a micro lens array that can be manufactured easily.